Transplantation: Deceased Donation of Organs

Question 1

What are the criteria for brain death?

Answer 1

Clinical evaluation: 1. Coma, 2. No brainstem reflexes, a. no pupillary response, b. no oculocephalic reflex, c. no corneal reflex, d. absence of facial movements to noxious stimuli, e. no tracheobronchial reflex, f. apnoea in response to acidosis or hypercarbia. BUT to determine all of these, the patient must my normothermic, have no major electrolyte or acid-base disturbance, not be on any drug that causes sedation or paralysis, be relatively normotensive, and have an established, irreversible cause for coma.

Question 2

What duration of ‘circulatory death’ is permissible should a person expect to recover their premorbid neurological function?

Answer 2

Studies suggest that in normothermic individuals, a down time of 10-11 minutes is probably the maximum amount of time.

Question 3

What are the Maastricht categories for non-heart beating donors

Answer 3

Cat 1: Dead on arrival
Cat 2: Unsuccessful resus
Cat 3: Brain dead, awaiting cardiac death
Cat 4: Cardiac death in a brain dead donor

Question 4

When to notify organ procurement organisations?

Answer 4

Any imminent death
Severe acute brain injury,
Ventilator dependent in ICU or ED, 4.
GCS <5,

OR

Non-recoverable neurological injury,
as soon as formal brain death examination is contemplated, or before initiating a discussion that would lead to withdrawal of life-support treatments.

Question 5

In what order are organs extracted during the harvest procedure?

Answer 5

1. Heart, 2. Lungs, 3. Liver (small intestine), 4. Pancreas, 5. Kidneys.

Question 6

What is warm ischaemia time?

Answer 6

Time between circulatory arrest and commencement of cold storage.

Question 7

After what duration of warm ischaemia time does DGF increase?

Answer 7

20 minutes

Question 8

What is cold ischaemia time?

Answer 8

The period of cold storage or machine perfusion

Question 9

What are the ideal durations for cold ischaemia time?

Answer 9

Less than 24 hours is acceptable, less than 12 hours is ideal.

Question 10

What is rewarm time?

Answer 10

The period between removal of the kidney from cold storage to reperfusion of the organ.

Question 11

How do you reduce the impact of rewarm time?

Answer 11

Wrapping the kidney in ice until the vascular anastomosis is completed.

Question 12

How is organ cooling achieved?

Answer 12

The organ is flushed with cold storage solutions (University of Wisconsin soln. or histidine tryptophan ketoglutarate) in situ before explantation and packaging. The soln. is cooled to 4 degrees celcius,

Question 13

What is the hypothermic pulsatile machine?

Answer 13

It delivers a dynamic flow of cold perfusate to the organ. Grafts with flows of 100-150ml/min and resistances of 0.2-0.4 are considered optimal.

Question 14

What are the benefits of the HPM?

Answer 14

Absolute reduction in DGF of 6%
Improved 1yr graft survival of 4%
Improved graft survival at 3 yrs (91% vs 87%)
(but effect was most pronounced in the ext criteria donors)

Question 15

What pharmacological adjuncts are used in deceased donation?

Answer 15

High dose corticosteroids
Vasopressin and T3 and T4 (data limited)
Mannitol (to maintain a diuresis)
Dopamine (minimal effect, may lower rate of DGF)
Systemic heparinisation